EP1253301B1

EP1253301B1 - Metal case of exhaust device and method of producing same

Info

Publication number: EP1253301B1
Application number: EP02009141A
Authority: EP
Inventors: Yasuhiro c/o Calsonic Kansei Corp. Nogami
Original assignee: Calsonic Kansei Corp
Current assignee: Marelli Corp
Priority date: 2001-04-24
Filing date: 2002-04-24
Publication date: 2005-03-30
Anticipated expiration: 2022-04-24
Also published as: DE60203432D1; DE60203432T2; US20020168303A1; EP1253301A3; EP1253301A2; JP2003013734A

Description

The present invention relates to a metal case of an exhaust device and to a method of producing a metal case of an exhaust device and to a catalytic converter comprising such a metal case.
In order to clarify the task of the present invention, a metal case 10 of a catalytic converter of an automotive engine, which has been widely employed, will be briefly described with reference to Fig. 6 of the accompanying drawings.
As shown in the drawing, the metal case 10 generally comprises an enlarged round center portion 10a, a tapered inlet portion 10b connected to an upstream end of the center portion 10a and a tapered outlet potion 10c connected to a downstream end of the center portion 10a. The enlarged round center portion 10a has a catalyst carrier installed therein. The inlet portion 10b has a diametrically reduced inlet pipe part 10b' that is to be connected to an upstream exhaust pipe leading to an exhaust manifold (not shown) of the engine, and the outlet potion 10c has a diametrically reduced outlet pipe part 10c' connected to a downstream exhaust pipe leading to a muffler (not shown).
Usually, the metal case 10 having the above-mentioned style is produced by a drawing process. That is, first, a cylindrical hollow body having the same diameter as the round center portion 10a is provided. Then, the hollow body is put on a suitable lathe and axially opposed portions of the hollow body are each tapered by pressing a pressing roller (not shown) thereto revolving the entire of the hollow body. The process is advantageous because of simple, low cost and easy production of the metal case 10.
However, as is seen from the drawing, due to a limited space available under a vehicle floor to which the catalytic converter is mounted, some of the metal cases 10 of the catalytic converter are compelled to have the inlet pipe part 10b' inclined relative to a longitudinal axis 12 of the converter by a given angle "". Thus, this type metal case 10 can not be produced by an ordinary drawing process in which the pressing roller moves in the direction of the arrow "z" and the hollow body (viz., work) moves in the direction of the arrow "y".
Accordingly, hitherto, an additional step has been employed. That is, after the case 10 is produced by using an ordinary drawing method, the inlet pipe part 10b' is bent by using a bending device. Furthermore, as is disclosed by Japanese Patent 2957154, a unique drawing process has been used in which after the cylindrical hollow body (viz., work) is set on a lathe with a certain inclination relative to the longitudinal axis 12, a pressing roller is pressed against the inlet pipe part 10b' revolving about the longitudinal axis 12.
However, the above-mentioned methods for providing the metal case 10 with the inclined inlet pipe part 10b' need a complicated, skilled and time-consumed technique, which has brought about a high cost production of the case. Furthermore, these methods tend to apply a marked stress to limited portions of the work where the pressing force of the pressing device or pressing roller is directly applied. Thus, if the stress is excessive, the portions tend to produce undesirable cracks.
An elastic support for a ceramic monolithic catalytic body can be taken from prior art document DE 2 209 487 A. Said monolithic body is supported within a casing, which is constituted by a cylindrically shaped mid section and connected with some pipe section having a diameter smaller than said mid section. The cylindrically shaped mid section and said pipe section are connected to each other by a tappert section bridging the respective different diameters. Said cylindrically shaped mid section and the pipe section are coaxially arranged. In order to protect the ceramic monolithic catalytic body against vibration and the like, folds are provided within said cylindrically shaped mid section and said pipe section.
It is an objective of the present invention to provide a metal case of an exhaust device and a method of producing a metal case of said exhaust device and a catalytic converter comprising such a metal case, wherein said metal case can be easily adapted to different purposes of arranging the exhaust device with high reliability and low costs.
According to an apparatus aspect of the present invention, said objective is solved by a metal case of an exhaust device having the features of independent claim 1.
Preferred embodiments are laid down in the dependent claims.
According to a method aspect of the present invention, said objective is solved by a method of producing a metal case of an exhaust device having the features of independent claim 8.
Preferred embodiments are laid down in the dependent claims.
Moreover, said objective is also solved by a catalytic converter having the features of claim 13.
Hereinafter, the present invention is illustrated and explained by means of preferred embodiments in conjunction with the accompanying drawings. In the drawings wherein:
Fig. 1 is a side view of a metal case of exhaust device, which is a first embodiment;
Fig. 2 is a view similar to Fig. 1, but showing a second embodiment;
Figs. 3A to 3D are views showing a method of producing the metal case of the first embodiment;
Fig. 4 is an enlarged sectional view of a part of the metal case of the first embodiment, depicting a step of bending an inlet pipe portion of the case;
Fig. 5 is a sectional view of a part of the metal case of the first embodiment, depicting another step of bending the inlet pipe portion of the case; and
Fig. 6 is a view similar to Fig. 1, but showing a conventional metal case of exhaust device.
Referring to Fig. 1, there is shown a metal case 100 of a catalytic converter, which is a first embodiment.
As shown in the drawing, the metal case 100 comprises an enlarged round center portion 100a that contains therein a catalyst carrier, a tapered inlet portion 100b connected to an upstream end of the center portion 100a and a tapered outlet portion 100c connected to a downstream end of the center portion 100a. The tapered inlet portion 100b has a diametrically reduced inlet pipe portion 100b' that is to be connected to an upstream exhaust pipe leading to an exhaust manifold (not shown) of the engine, and the tapered outlet portion 100c has a diametrically reduced outlet pipe portion 100c' that is to be connected to a downstream exhaust pipe leading to a muffler (not shown).
Between the tapered inlet portion 100b and the inlet pipe portion 100b', there are integrally formed accordion folds or bellows 100d, and similar to this, between the tapered outlet portion 100c and the outlet pipe portion 100c', there are integrally formed accordion folds or bellows 100e. Due to provision of the accordion folds 100d and 100e which have been plastically deformed, the inlet and outlet pipe portions 100b' and 100c' are inclined relative to a longitudinal axis 102 of the metal case 100 by a given angle "α". As is seen from the drawing, the accordion folds 100d and 100e are identical in shape, including the same number of pleats or folds.
In the following, method of producing the metal case 100 will be described with reference to Figs. 3A to 3D.
First, as is seen from Fig. 3A, a cylindrical hollow body 100A of stainless steel, copper or the like is prepared. Then, a catalyst carrier 150 is inserted into a center position of the cylindrical hollow body 100A.
Then, the cylindrical hollow body 100A is set on a lathe (not shown), and as is seen from Fig. 3B, axially opposed portions of the cylindrical hollow body 100A are each drawn by pressing a pressing roller (not shown) thereto revolving the entire of the cylindrical hollow body 100A about a longitudinal axis 102. That is, during this process, the pressing roller moves in the direction of the arrow "z" and the cylindrical hollow body 100A (viz., work) moves in the direction of the arrow "y". With this drawing step, tapered inlet and outlet portions 100b and 100c protruding from an enlarged center portion 100a are produced. By continuing the drawing process by the pressing roller, inlet and outlet pipe portions 100b' and 100c' are also produced. With these steps, a first semi-finished aligned product 100B is prepared, which comprises the enlarged center portion 100a, the tapered inlet and outlet portions 100b and 100c and the diametrically reduced inlet and outlet pipe portions 100b' and 100c', which are all aligned along the longitudinal axis 102.
Then, as is seen from Fig. 3C, the pressing roller is applied to a junction portion between the tapered inlet or outlet portion 100b or 100c and the inlet or outlet pipe portion 100b' or 100c', and pressed thereto strongly and lightly periodically, revolving the first semi-finished product 100B about the longitudinal axis 102 while moving the same along the longitudinal axis 102. With this, accordion folds 100d and 100e aligned with the longitudinal axis 102 are produced. Thus, a second semi-finished aligned product 100C is produced as is shown in Fig. 3C. If this folds-producing process is actually carried out while the first semi-finished aligned product 100B keeps a certain higher temperature, the process is much easily and assuredly carried out because a work-hardening can be avoided.
Then, the second semi-finished product 100C is brought to a hydraulically powered bending device for bending the inlet and outlet pipe portions 100b' and 100c relative to the longitudinal axis 102 by the given angle "α". That is, as is seen from Fig. 4, the inlet and outlet pipe portions 100b' and 100c' are respectively held by first clamps 104 (only one is shown) and the tapered inlet and outlet portions 100b and 100c are respectively held by second clamps 106 (only one is show). Then, cylindrical bars 108 (only one is shown) are respectively and intimately put into the inlet and outlet pipe portions 100b' and 100c'. Then, both the cylindrical bars 108 and the first clamps 104 are pulled in the direction of the arrow "x" with the aid of hydraulic power. With this, as shown in Fig. 3D, the accordion folds 100d and 100e are plastically deformed inclining the inlet and outlet pipe portions 100b' and 100c' relative to the longitudinal axis 102 by the angle "α". With these steps, the metal case 100 is produced.
If desired, as is shown in Fig. 5, in place of the above-mentioned second clamps 106 by which the tapered inlet and outlet portions 100b and 100c are held, a simpler clamp 110 may be used which holds the enlarged center portion 100a of the second semi-finished product 100C. Also in this case, the first clamps 104 holding the inlet and outlet pipe portions 100b' and 100c' and the cylindrical bars 108 intimately put in the inlet and outlet pipe portions 100b' and 100c' are employed, and bending of the inlet and outlet pipe portions 100b' and 100c' is carried out by pulling both the cylindrical bars 108 and the first clamps 104 in the direction of the arrow "x".
As is described hereinabove, due to provision of the accordion folds 100d and 100e which show a certain flexibility and plasticity, the bending of the inlet and outlet pipe portions 100b' and 100c' is readily and assuredly made without inducing a possibility of producing undesirable cracks. That is, due to the nature of the accordion folds 100d and 100e, the bending of the inlet and outlet pipe portions 100b' and 100c' is carried out by shrinking or expanding certain portions of the accordion folds 100d and 100e without making a reduction in plate thickness. That is, as is seen from Fig. 4, under bending of the inlet pipe portion 100b' in the direction of the arrow "x", upper portions of the accordion folds 100d are subjected to shrinkage and lower portions of the same are subjected to expansion. However, these shrinking and expanding movements of the accordion folds 100d do not induce reduction in thickness of the plate material of the folds 100d. In other words, the mechanical strength of the accordion folds 100d is kept unchanged even when the inlet pipe portion 100b' is bent.
Referring back to Fig. 2, there is shown a case 200 of a catalytic converter, which is a second embodiment.
In this second embodiment 200, the number of pleats of the accordion folds 100d is greater than that of the accordion folds 100e. Furthermore, the accordion folds 100d largely enter the tapered inlet portion 100b. More specifically, the accordion Folds 100d comprise first and second groups of accordion folds 100d-a and 100d-b which are separated at their mating part. Thus, the inlet pipe portion 100b' can be much largely inclined (viz., angle "β") relative to the longitudinal axis 102 as compared with of the outlet pipe portion 100c' (viz., angle "α"). Due to provision of the first and second groups of accordion folds 100d-a and 100d-b, a so-called two step bending is achieved for the inlet pipe portion 100b'. That is, a plastic deformation degree of the first group of accordion folds 100d-a is larger than that of the second group of accordion folds 100d-b.
As is described hereinabove, according to the present teaching, the cylindrical hollow body 100A is subjected to a drawing process to provide the first semi-finished aligned product 100B as shown in Fig. 3B. Then, the first semi-finished aligned product 100B is subjected to a folds-producing process to provide the second semi-finished aligned product 100C as shown in Fig. 3C. Then, the second semi-finished aligned product 100C is held by clamping means including the second clamps 106 or the third clamp 110, and bending of the inlet and outlet pipe portions 100b' and 100c' of the second semi-finished product 100C is carried out with the aid of the first clamps 104 and the cylindrical bars 108. Thus, bending of the inlet and outlet pipe portions 100b' and 100c' is readily and assuredly carried out without sacrificing mechanical strength of a part of the case 100 where the bending is actually made.
Furthermore, according to the present teaching, for.bending the inlet or outlet pipe portion 100b' or 100c', the major portion of the second semi-finished product 100C is tightly held by clamping means and both the first clamp 104 holding the inlet or outlet pipe portion 100b' or 100c' and the cylindrical bar 108 intimately put in the inlet or outlet pipe portion 100b' or 100c' are pulled in the given direction "x". Thus, the inlet or outlet pipe portion 100b' or 100c' can be accurately bent by a desired angle.
If desired, for bending the inlet or outlet pipe portion 100b' or 100c' relative to the longitudinal axis 102, the major portion of the second semi-finished product 100C may be pulled or pushed in a given direction keeping both the first clamp 104 and the cylindrical bar 108 at their fixed positions.
In the above-mentioned first and second embodiments, each metal case 100 or 200 has two accordion folds 100d and 100e at axially opposed portions thereof. However, if desired, the case 100 or 200 may have only one accordion folds at one axially end portion. Of course, in this case, the inlet or outlet pipe portion extending from the accordion folds is subjected to the inclination due to plastic deformation of the accordion folds.

Claims

A metal case of an exhaust device, comprising:

an enlarged round center portion (100a) having a longitudinal axis (102);

first and second tapered portions (100b, 100c) respectively connected at diametrically larger ends thereof to axially opposed ends of said enlarged round center portion (100a);

first and second pipe portions (100b', 100c') respectively

connected to diametrically smaller ends of said first and second tapered portions (100b, 100c) respectively; characterised by at least first accordion folds (100d) defined by and between said

first tapered portion (100b) and said first pipe portion (100b');

wherein said first pipe portion (100b') is bent relative to said longitudinal axis (102) as a result of plastic deformation of said accordion folds (100d, 100e).
A metal case of an exhaust device according to claim 1, further comprising:

second accordion folds (100e) defined by and between said second tapered portion (100c) and said second pipe portion (100c').
A metal case of an exhaust device according to claim 2, wherein said first and second pipe portions (100b', 100c') are bent relative to said longitudinal axis (102) as a result of plastic deformation of said first and second accordion folds (100d, 100e).
A metal case according to at least one of the claims 1 to 3, wherein said enlarged round center portion (100a), said first and second tapered portions (100b, 100c), said first and second pipe portions (100b', 100c') are integrally connected to one another to provide a monolithic structure.
A metal case according to claim 4, wherein said monolithic structure is made of stainless steel plate or copper plate.
A metal case according to at least one of the claims 1 to 5, wherein said accordion folds (100d) comprise:

first group of accordion folds (100d-a);

second group of accordion folds (100d-b); and

a mating round portion through which said first and second groups of accordion folds (100d-a, 100d-b) are connected,

wherein plastic deformation degree of said first group of accordion folds (100d-a) is different from that of said second group of accordion folds (100d-b).
A metal case according to claim 7, wherein said first group of accordion folds (100d-a) is defined by said first inlet pipe portion (100b') and said second group of accordion folds (100d-b) is defined by said first tapered portion (100b).
A method of producing a metal case of an exhaust device, comprising the steps of:

(a) preparing a round hollow body (100A) of metal;

(b) subjecting said round hollow body (100A) to a drawing process to provide a first semi-finished aligned product (100B) which comprises an enlarged round center portion (100a), first and second tapered portions (100b, 100c) respectively connected at diametrically larger ends thereof to axially opposed ends of said enlarged round center portion (100a), and first and second pipe portions (100b', 100c') respectively connected to diametrically smaller ends of said first and second tapered portions (100b, 100c) respectively;

(c) subjecting said first semi-finished aligned product (100B) to a folds-producing process to produce and define at least first accordion folds (100d) between said first tapered portion (100b) and said first pipe portion (100b') thereby to provide a second semi-finished aligned product (100C);

(d) holding a major portion of said second semi-finished aligned product (100C) to a fixed member (104, 106, 110); and

(e) applying a given force to said first and second pipe portion in a manner to induce a plastic deformation of said accordion folds (100d, 100e) thereby to bend the pipe portion relative to a longitudinal axis (102) of said major portion of said second semi-finished aligned product (100C).
A method of producing a metal case of an exhaust device according to claim 8, comprising the steps of:

(c) subjecting said first semi-finished aligned product (100B) to a folds-producing process to produce and define said first accordion folds (100d) between said first tapered portion (100b) and said first pipe portion (100b') and second accordion folds (100e) between said second tapered portion (100c) and said second pipe portion (100C') thereby to provide said second semi-finished aligned product (100C);

(e) applying a given force to at least one of said first and second pipe portions (100b', 100c') in a manner to induce a plastic deformation of corresponding one of said first and second accordion folds (100d, 100e) thereby to bend the pipe portion relative to a longitudinal axis (102) of said major portion of said second semi-finished aligned product (100C).
A method of producing a metal case of an exhaust device according to claim 8 or 9, wherein the step (e) comprises:

(f) holding said pipe portion by a clamp (104);

(g) inserting a round bar (108) into said pipe portion (100b'); and

(h) pulling both said clamp (104) and said round bar (108) in a given direction (x) with the given force.
A method of producing a metal case of an exhaust device according to at least one of the claims 8 to 10, wherein the step (d) comprises:

(i) holding said first and second tapered portions (100b, 100c) by respective clamps (106).
A method of producing a metal case of an exhaust device according to at least one of the claims 8 to 10, wherein the step (d) comprises:

(j) holding said enlarged round center portion (100a) by a clamp (110).
A catalytic converter comprising:

a metal case (100, 200) according to at least one of the claims 1 to 7 and

a catalyst carrier (150) tightly installed in said enlarged round center portion (100a) of said metal case (100, 200).